Errors

All lob errors are values, never exceptions. Builder::Build() writes one LobErrorT / lob::ErrorT into Context::error; every LobSolve* checks it first and returns 0 on any non-kNone (source/lob_solve.cpp). Builder never throws and never allocates — setters overwrite stored values, Build() stops at the first failing stage and reports that error only.

kLobErrorNotFormed is internal (sentinel before any stage runs) and never exposed from a successful Build(); kLobErrorNumberOfErrors is the count.

Catalog

`LobErrorT`	Trigger (first failing `Build*` stage)
`kNone`	success
`kBallisticCoefficientRequired`	no drag source and no `BallisticCoefficientPsi`
`kBallisticCoefficientOOR`	`BC ≤ 0`
`kInitialVelocityRequired`	missing or `≤0` fps (`BuildStability`)
`kZeroDataRequired`	neither `ZeroAngleMOA` nor `ZeroDistanceYds`
`kZeroDistanceOOR`	`ZeroDistanceYds ≤ 0`
`kZeroAngleOOR`	explicit `abs(ZeroAngleMOA) > 45°`
`kZeroUnreachable`	`SolveAngle` returns NaN for the zero distance (vacuum-parabola seed, 10 iters, ±45°)
`kRangeAngleOOR`	`abs(RangeAngleDeg) ≥ 90°`
`kDiameterOOR` / `kLengthOOR` / `kMassOOR`	non-positive geometry needed for `stability_factor`
`kMeplatDiameterOOR` / `kBaseDiameterOOR` / `kNoseLengthOOR` / `kTailLengthOOR` / `kOgiveRtROOR`	Boatright geometry out of `[0,∞)` or `ogiveRtR ∉ [0,1]`
`kAltitudeOfFiringSiteOOR` / `kAltitudeOfBarometerOOR` / `kAltitudeOfThermometerOOR`	`abs(alt) ≥ 65 617 ft` (`kStratosphereAltitudeFt`)
`kAirPressureOOR`	`AirPressureInHg < 0`
`kHumidityOOR`	`RelativeHumidityPercent ∉ [0,100]`
`kAzimuthOOR`	`abs(azimuth) > 360°`
`kLatitudeOOR`	`abs(latitude) > 90°`
`kWindHeadingOOR`	internal `wind_heading_rad` outside `±360°`
`kMaximumTimeOOR`	`MaximumTime < 0`
`kMachDragTableTooShort`	`size < 2`
`kMachDragTableNotMonotonic`	Machs not strictly increasing
`kMachDragTableInvalid`	`Mach < 0`, `Cd < 0`, non-finite, or cubic extrapolation negative at 0/5
`kBcBandsTooShort`	`size < 2`
`kBcBandsInvalid`	`size > 16`, any `fps ≤ 0` / `BC ≤ 0` / non-finite, or `max(fps)/c ≥ 5.0`
`kBcBandsNotMonotonic`	`fps` not strictly increasing
`kInternalError`	Boatright supersonic integration to `Mach 1.2` exceeded 60 s (temporary guard)
`kNotFormed`	internal sentinel — not returned
`kNumberOfErrors`	count

C names are in include/lob/lob.h; C++ scoped names are lob::ErrorT::k* (include/lob/lob.hpp). Build() order is BuildEnvironment → BuildSpline → BuildCoefficients → BuildWind → BuildOpticHeight → BuildStability → BuildCoriolis → BuildBoatright → BuildLitzAerodynamicJump → BuildOptions → BuildZeroAngle (source/lob_builder.cpp LobBuilderBuild) — first failure wins.

Handling

lob::Context ctx = lob::Builder().BallisticCoefficientPsi(0.5).Build();
if (ctx.error != lob::ErrorT::kNone) {
  // ctx.error is one of the rows above; no throw, no alloc
}
size_t n = lob::Solve(ctx, ranges, &outs); // returns 0 if ctx.error != kNone

LobSolve/LobSolveInverse also return 0 on null pointers, size==0, non-finite zero_angle, velocity==0, speed_of_sound≤0, or non-monotonic pranges — those are solve-time guards, not LobErrorT.